I think that the complainants, petitioners in No. 34, are proper parties to maintain this suit, that the decree' should be reversed and, on the remand, the petition of Kansas City for intervention should be considered in light of that conclusion and of § § 212 and 213 of the Judicial Code, 28 U. S. C. § 45a and of Rule 24 of the Rules of Civil Procedure.
On the pleadings it stands conceded that the proposed extension of respondent’s line is unauthorized and unlawful, and the sole question we have ■ to decide is whether the interest of petitioners in maintaining this suit, as disclosed by their pleadings, satisfies the requirement of the statute which authorizes it to be brought by “any party in interest.”
Section 1 (18) of the Transportation Act of 1920, 41 Stat. 474, 477, 49 U. S. C. § 1 (18), forbids the extension of its line by a railroad without a certificate of the Interstate Commerce Commission that “the present or future public convenience and necessity require or will require” the construction of the extension. Similarly it prohibits the abandonment of any portion of a line of railroad without a like certificate permitting the abandon*309ment. Section 1 (19) requires the Commission to give notice of application for a certificate to the governor of the state in which the proposed extension is to be constructed and to publish the notice in each county through which the line of railroad is constructed or operated. By § 1 (20) the Commission -is authorized to attach to its certificate such “conditions as in its judgment the public convenience and necessity may require,” and authorizes any court of competent jurisdiction to enjoin the prohibited construction or abandonment “at the suit of the United States, the Commission, any commission or regulating body of the state or states affected, or any party in interest; ...” By § 1 (22) spur, industrial, side tracks and the like are excluded from the authority of the Commission and the railroad may build them without applying for a certificate.
The interest of petitioners in maintaining the suit as shown by the pleadings is derived from the injury to the public which, it is specifically alleged, will result from the proposed extension through the injury to the community in Kansas City, Missouri, and vicinity, of which community petitioners are a part and in which they are property owners, and the consequent injury alleged to affect them individually. The public injury, it is alleged, will be caused by (a) the loss or serious impairment in utility of the Kansas City public produce market and the destruction or serious diminution of values of property and business and of financial investments in and about the market, which will be brought about by the extension, through the creation of a rival market- and the diversion of traffic to iff'at a point in Kansas City, Kansas, far removed from the center of population of Kansas City, Missouri, and to the inconvenience of the great majority of the citizens of both cities who are served by the existing market, which is adequate to the needs of the community; (b) by the *310unnecessary duplication of railroad facilities m the Kansas City district at large cost, with wasteful and needless expenditures by respondent and no increase in freight to be handled; and (c) by the diversion of traffic to respondent railroad from other railroads and destructive competition between the railroads operating in the vicinity.
Special injury is shown to complainants (petitioners in No. 34) by the allegations that they are owners of business property and investments in the existing market area and vicinity, and that their property will be reduced in value in consequence of the diversion of traffic to the rival market. The petitioner, Kansas City, Missouri, in intervention, in No. 35, alleges the like injury to the public which it represents and sets up. specifically the threatened loss in value and utility of a large public market structure which it is now building at great cost, and the threatened loss to it of taxes through diminution in property values in the city.
■ The statute does not define the “parties in interest” whom it permits to sue to restrain an unauthorized extension. It cannot be assumed that the phrase is meaningless or that the statute should be read as though the words were omitted. Obviously the parties intended must have, as do petitioners, an interest in the outcome of the litigation other than the “common concern for obedience, to law.” See Massachusetts v. Mellon, 262 U. S. 447, 488. And as the language of the statute plainly indicates, and as we have held, they may be, as are petitioners, others than the public bodies named in the statute as appropriate plaintiffs. Atchison, T. & S. F. Ry. Co. v. Railroad Commission, 283 U. S. 380, 393, 394. And they may maintain the suit although the injury which they allege is not strictly an actionable wrong independently of the paragraphs in question. *311Western Pacific R. Co. v. Southern Pacific Co., 284 U. S. 47.
The statute draws no distinction between direct and indirect injury as the test of plaintiff’s interest- Nor is any reason advanced for saying that his interest is more significant because the injury which he suffers is labeled “direct” rather than “indirect.” In any case, that suffered by petitioners does not seem to be any the less direct than that which an extension may inflict upon a competing railroad which admittedly may sue to enjoin it. Western Pacific R. Co. v. Southern Pacific Co., supra; cf. Claiborne-Annapolis Ferry Co. v. United States, 285 U. S. 382. If the statute imposes any requirements other than those indicated' by the phrase “party in interest,” they must be implied from the purposes of the statute, its context, and from the reasons for permitting others than the public bodies named in it to bring the suit. Cf. New York Central Securities Co. v. United States, 287 U. S. 12, 24. On the other hand if maintenance of the present suit by petitioners is consistent with those purposes and aids them and is in harmony with the reasons for allowing any party in interest to sue, the conclusion would seem inescapable that petitioners are proper plaintiffs.
It is not denied that the statutory language and the legislative history of the paragraphs in question require consideration by the Commission of the interests of cities, towns and communities which are adversely affected by a proposed extension of a line of railroad, in order to determine whether “public convenience and necessity” require the extension. The phrase “public convenience and necessity” has long been used to signify the final result of the balancing of the consequences which flow from the proposed action to all those matters of public concern which are affected by it. Cf. Chesa*312peake & Ohio Ry. Co. v. United States, 283 U. S. 35, 42; United States v. Lowden, 308 U. S. 225. And we have held that in the administration of the cognate provision relating to abandonment of railroad lines the Commission must consider as a part of the public convenience and necessity the interests of local communities affected by the proposed abandonment. Colorado v. United States, 271 U. S. 153, 168. A community may suffer injury through the loss of railroad service and diversion of traffic resulting from the construction and operation of a railroad extension without any compensating public advantage which is comparable in kind and amount with injury sustained by the abandonment of a line of railroad. One as well as the other should receive the consideration of the Commission in determining whether it should grant or withhold.a certificate. Such appears to be its settled practice on applications for a certificate authorizing extension.1
*313It is plain that the purpose of the statute is the protection of the public interest and that in the administration of its provisions by the Commission public interest is of paramount concern. That interest is primarily. that railroad extensions, as the statute provides, shall not be built or operated without receiving the approval of the Commission, and that the Commission shall grant its permission only if the public convenience and necessity so require.
In determining who may bring the suit to restrain the proposed construction as provided by § 1 (20), it is significant that the suit is brought-to restrain an act which the statute declares unlawful, the construction of an .extension without the certificate of the Commission, §-1 (18), and that the function of the court is not that of the Commission in granting or withholding a certificate. The only issue which can be litigated in such a suit, brought by a proper plaintiff, is whether in fact the proposed construction is of a spur or sidetrack, the only new trackage which a railroad may lawfully build without recourse to' the Commission. It is an issue which is by paragraphs (18) and (22) of § 1 made a judicial, not an administrative question and involves no more ■complexities of litigation than many other cases which courts are called on daily to decide. In any case the issue is ■ one which Congress directed to be litigated in a suit brought under §' 1 (20), and its complexity is unaffected by the particular plaintiff who brings the suit. ■
If the proposed construction is an extension the injunction must issue, as of right, but- its only effect is to compel the railroad before proceeding further to apply to the Commission for a certificate of public convenience and necessity which is the public purpose of the Act. *314Texas & Pacific Ry. Co. v. Gulf, C. & S. F. Ry. Co., 270 U. S. 266, 273. The court is thus called on to decide no administrative issue which must be submitted to the Commission in advance of suit, and any decree which it may render involves no embarrassment to the Commission or otherwise in the administration of the Act. While the Commission itself may bring the suit, it is under no statutory duty to do so and its only other authority in the premises is to grant or withhold the certificate when applied for. One injured by an unauthorized extension and opposed to its construction, whether a state commission, a competing railroad or any other injured party, is not authorized to initiate any proceeding before the Commission and its only protection as of right from the consequences of the threatened public wrong is that afforded by suit authorized by § 1 (20). See Texas & Pacific Ry. Co. v. Gulf, C. & S. F. Ry. Co., supra, 272-274.
In considering the scope of the application of the statute tifié Court has recognized that the public interest' which the Commission is to protect includes the public interest in the maintenance of an adequate transportation system and that a railroad whose welfare, although not its legal right, is adversely affected by an unauthorized and therefore unlawful extension of the line of another is a “party in interest” entitled to maintain suit to enjoin the extension. Western Pacific R. Co. v. Southern Pacific Co., supra; cf. Claiborne-Annapolis Ferry Co. v. United States, supra. And it has held that one other than a carrier (a municipality),'who has “a proper interest in the subject matter,” may institute a proceeding before the Interstate Commerce Commission under § 1, paragraphs 18 to 22, to obtain a certificate of public convenience, so as to .enable a railroad' to build an extension to a new station which a state commission has ordered it to build. Atchison, T. & S. F. Ry. Co. v. *315Railroad Commission, supra, 393, 394. Compare Detroit & M. Ry. Co. v. Boyne City, G. & A. R. Co., 286 F. 540.
But it has never held, unless it has done so now, that the public concern in protecting large communities from destruction of their business and financial interests by diversion of traffic to rival communities by railroad extensions, is not included in that public convenience and necessity which the Commission must consider in granting or withholding a certificate; or that one not a railroad who is a member of a community adversely affected and whose own business or property interests are so adversely affected is not a “party in interest” within the meaning of the statute.
If the statute permits some protection through commission action of the public interest in the preservation of communities adversely affected by the construction of railroad extensions, no plausible reason has been advanced for saying that an individual member of such a community whose property or financial interests are adversely affected by the proposed unauthorized extension, and who would be a proper party to the proceeding before the Commission on application for a certificate,2 *316is not a party in interest, entitled to bring suit quite as much as a competing railroad whose property interests are likewise affected. On the contrary, petitioners have a special and peculiar interest in preventing the unlawful extension and in.securing, before the extension is built, such consideration of the community interest as the Commission gives, and which can be insured only by resort to the suit authorized by § 1 (20).
True, the statute is concerned with the protection of the public interest but in order that the public interest might not suffer, and that private injury might not be inflicted through a public wrong, the construction of an unlawful extension, Congress did not restrict the authority to bring suit to public agencies — the United States, the Commission or state commissions. Congress by providing that applications for certificates of convenience need not be made for local spur or side tracks, recognized that such constructions are too trivial to require a proceeding before the Commission. Instead it gave authority to bring the suit- to private parties in interest, who because of the injury especially inflicted upon them through the adverse effect of the unlawful' extension on the public, have a peculiar .incentive to protect the public interest with which the statute is concerned, see Federal Communications Comm’n v. Sanders Bros. Radio Station, 309 U. S. 470, 477, and who by restraining an unauthorized “extension” insure the expert consideration by the Commission in the situation in which Congress required it.
Just as Congress gave authority to a railroad to sue to enjoin an unauthorized extension by its competitor in order to effect the railroad policy of the Act, it gave like authority to complainants to effect its public policy with respect to a community injuriously affected by an *317unlawful'railroad extension. The statute gives no warrant for saying that the one may bring suit but that the other can only ask some public body' to bring it; and neither interferes with the functions which the Commission is authorized to perform and which, as we have seen, are distinct from those assigned to the court by § 1 (20).
Maintenance .of- the suit by complainants is thus within the fair meaning of the words of the statute. It aids rather than obstructs the administration of the Act; it effectuates the public policy of the Act and is within the reason for permitting others than public agencies to bring the suit. They are “parties in interest” to which the statute refers.
Since the suit was properly brought the district court should entertain and decide the petition of Kansas City for intervention in the light of 28 U. S. C. § 45a and Rule 24 of the Rules of Civil Procedure.
The Chief Justice and Mr. Justice Reed concur in this opinion.See Aroostook Valley R. Co., Construction, 105 I. C. C. 643; Minnesota Western R. Co., Construction, 111 I. C. C. 377; Northern Oklahoma Rys., Construction, 111 I. C. C. 765; Construction of Piedmont & Northern Ry. Co., 138 I. C. C. 363; Western Pacific California R. Co., 162 I. C. C. 5. And in balancing the public conveniences and necessities involved, that is to say the public interest in an adequate transportation system and the public interest in protecting local communities from undue injury from extensions of relatively small transportation importance, the Commission has sometimes found the injury to existing community interests persuasive ground for refusing the certificate. Construction by Aroostook Valley R. Co., supra; Construction by Minnesota Western R. Co., supra.
The broad scope of. the Commission’s inquiry is evidenced by the questionnaire which applicants for an extension must answer. Among the data required 'is the nature of the population, the territory, the industries involved, the names and character of towns near to but not served by the extension. See In the matter of Applies tions under Paragraphs (18) and (21), Inclusive, Section 1, of the Interstate Commerce Act for Certificates of Public Convenience and Necessity for the Construction or Extension of Lines of Railroad, *313January 22, 1924. III-A Sharfman, The Interstate Commerce Commission, 333-335, 351.
It is settled policy _of tbe Interstate Commerce Act and related statutes to permit shippers, cities, commercial organizations and other interested parties to participate in proceedings before the Commission and in those before the courts where the application of the statute is involved. Section 9, 24 Stat. 382, 49 U. S. C. § 9, permits any person “claiming to be damaged” by a carrier to make complaint to the Commission or to bring suit in a district court. Communities, shippers and associations may make complaint to the Commission under § 13 (1), 49 U. S. C. § 13 (1), 24 Stat. 383 as amended, ’.36 Stat. 550. See, United States v. Merchants & Manufacturers Traffic Assn., 242 U. S. 178. Section 42 provides that in actions to stop rebates and concessions “all persons interested in or affected by the rate or regulation or practice” may be made parties. Sections 212 and 213 of the Judicial Code, 28 U. S. C. § 45a, provide that “com.munities, associations, corporations, firms and individuals who are *316interested in the controversy or question” before the Commission or in any suit which may be brought under the Act may intervene.